The present invention relates to the automation of proximate analyzers and the like, and more particularly, to apparatus and a method for opening and closing crucibles during such analysis.
Systems for proximate analysis of fossil fuels such as coal and coke through the use of heat are well known. The samples are subject to a heating and cooling cycle in a furnace chamber. The samples are in crucibles. The crucibles are in turn seated on a platter or carousel positioned within the chamber. At various times during the cycle the crucibles are covered or uncovered through the placing or removal of crucible covers. A weighing platform is positioned within the furnace chamber. The carousel continuously deposits the crucibles in a predetermined sequence on the weighing platform and the weights of the crucibles monitored to calculate the contained volatiles based on weight loss during heating.
U.S. Pat. No. 4,522,788, to Sitek et al., issued on Jun. 11, 1985, is directed to such a system. In this patent, the crucibles are placed manually on a carousel and covered and uncovered manually during the analysis. The crucibles are uncovered for initial weighing and then heated in nitrogen atmosphere to remove moisture content from the samples in them, the covers are then remounted by hand and the crucibles are heated to a higher temperature also in a nitrogen atmosphere to obtain volatiles, cooled, removed by hand in the presence of nitrogen atmosphere and heated again in oxygen atmosphere to obtain ash. In order to make such analyses more efficient and safer there is a need for a proximate analysis system that can automatically cover and uncover a series of crucibles at the appropriate stages of the analysis without requiring manual intervention.